linux-kernel - [PATCH 2/6] MIPS: jz4740: Acquire and enable DMA controller clock

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Date:	Thu, 23 May 2013 22:36:23 +0200
From:	Lars-Peter Clausen <lars@...afoo.de>
To:	Ralf Baechle <ralf@...ux-mips.org>,
	Vinod Koul <vinod.koul@...el.com>,
	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>
Cc:	Maarten ter Huurne <maarten@...ewalker.org>,
	linux-mips@...ux-mips.org, linux-kernel@...r.kernel.org,
	alsa-devel@...a-project.org, Lars-Peter Clausen <lars@...afoo.de>
Subject: [PATCH 2/6] MIPS: jz4740: Acquire and enable DMA controller clock

From: Maarten ter Huurne <maarten@...ewalker.org>

Previously, it was assumed that the DMA controller clock is not gated
when the kernel starts running. While that is the power-on state, it is
safer to not rely on that.

Signed-off-by: Maarten ter Huurne <maarten@...ewalker.org>
Signed-off-by: Lars-Peter Clausen <lars@...afoo.de>
---
 arch/mips/jz4740/dma.c | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/arch/mips/jz4740/dma.c b/arch/mips/jz4740/dma.c
index 317ec6f..0e34b97 100644
--- a/arch/mips/jz4740/dma.c
+++ b/arch/mips/jz4740/dma.c
@@ -16,6 +16,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/spinlock.h>
+#include <linux/clk.h>
 #include <linux/interrupt.h>
 
 #include <linux/dma-mapping.h>
@@ -268,6 +269,7 @@ static irqreturn_t jz4740_dma_irq(int irq, void *dev_id)
 
 static int jz4740_dma_init(void)
 {
+	struct clk *clk;
 	unsigned int ret;
 
 	jz4740_dma_base = ioremap(JZ4740_DMAC_BASE_ADDR, 0x400);
@@ -277,11 +279,29 @@ static int jz4740_dma_init(void)
 
 	spin_lock_init(&jz4740_dma_lock);
 
-	ret = request_irq(JZ4740_IRQ_DMAC, jz4740_dma_irq, 0, "DMA", NULL);
+	clk = clk_get(NULL, "dma");
+	if (IS_ERR(clk)) {
+		ret = PTR_ERR(clk);
+		printk(KERN_ERR "JZ4740 DMA: Failed to request clock: %d\n",
+				ret);
+		goto err_iounmap;
+	}
 
-	if (ret)
+	ret = request_irq(JZ4740_IRQ_DMAC, jz4740_dma_irq, 0, "DMA", NULL);
+	if (ret) {
 		printk(KERN_ERR "JZ4740 DMA: Failed to request irq: %d\n", ret);
+		goto err_clkput;
+	}
+
+	clk_prepare_enable(clk);
+
+	return 0;
+
+err_clkput:
+	clk_put(clk);
 
+err_iounmap:
+	iounmap(jz4740_dma_base);
 	return ret;
 }
 arch_initcall(jz4740_dma_init);
-- 
1.8.2.1

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